The present invention relates to sockets for electrically coupling a daughterboard to a motherboard. More particularly, the present invention relates to an apparatus that increases the retention force on the daughterboard to maintain an electrical connection between the daughterboard and the motherboard under rough or stressful operating conditions.
The size of computers has been reduced in the past several years. Therefore, computers have become more portable and movable. Movement of the computers can cause shock and vibrations which increases the amount of stress placed on electrical components within the computer. This stress can cause movement of the electrical components which can break or interrupt the electrical connection between the electrical components.
Because of the increased portability of computers, electrical components within the computer must be able to withstand an increased amount of shock and vibration. Computers include a main printed circuit board or motherboard. Additional printed circuit boards or daughterboards must be electrically coupled to the motherboard. Illustratively, the daughterboard may be a single In-line Memory Module (SIMM). A socket is configured to receive a daughterboard and acts as an electrical interconnection between the daughterboard and the motherboard to which the socket is mounted. Problems can arise upon dislocation of daughterboards from sockets coupled to the motherboard. Such dislocation may cause intermittent or failed signal path connections between the daughterboard and motherboard.
The present invention is designed to increase the retention force between a daughterboard and a socket coupled to a motherboard to stabilize the daughterboard within the socket. This reduces the likelihood that the daughterboard will "walk out" or dislodge from the socket.
Conventional sockets such as SIMM sockets are well known. Such conventional SIMM sockets include a plurality of electrical contacts which are electrically coupled to the motherboard. The sockets also include a pair of elongated module-receiving slots extending along a longitudinal axis of the socket for receiving a pair of daughterboards therein. The contacts engage conductive portions formed on the daughterboards inserted into the module-receiving slots to electrically couple the daughterboards to the motherboard. In conventional SIMM sockets, the daughterboards are stabilized by stabilizing beams formed integrally with the socket.
Typically, conventional SIMM sockets include an internal stabilizing beam and a pair of external stabilizing beams. In some conventional SIMM sockets, the external stabilizing beams are movable relative to the internal stabilizing beam. See, for example, U.S. Pat. No. 5,013,264. In other instances, a pair of internal stabilizing beams are movable relative to the external stabilizing beams. See, for example, U.S. Pat. No. 4,973,270. The internal and external stabilizing beams provide a frictional force against the daughterboards installed in the SIMM socket. While the retention force of the conventional stabilizing beams may be suitable for stable environments, the retention force may be insufficient if the SIMM socket is used in a stressful environment and subjected to shock and vibration.
It is also known to provide a metal latch to retain a daughterboard in a SIMM socket. Such metal latches typically hold an aperture formed in the daughterboard in a predetermined position over a locator pin or stop member integrally formed on the socket housing. A user must typically manually displace the latch in order to release the daughterboard from the socket. See, for example, U.S. Pat. No. 4,986,765; U.S. Pat. No. 4,995,825; U.S. Pat. No. 5,013,257; U.S. Pat. No. 5,064,381; and U.S. Pat. No. 5,094,624. Other conventional connectors are formed to include integral latch arms which engage holes formed in a substrate. See, for example, U.S. Pat. No. 4,725,250 and U.S. Pat. No. 4,781,612. It is often undesirable to require a user to manually displace a latch in order to remove the daughterboard. Several SIMM sockets are often arranged very close together on a motherboard. Therefore, it is often difficult to access a latch to release the daughterboards.
The present invention is designed to provide an increased retention force between the socket and the daughterboard. Advantageously, however, the present invention does not require the user to displace the retaining means manually in order to remove the daughterboard from the socket. Therefore, the present invention advantageously provides a socket having an improved retention force compared to conventional sockets having internal and external stabilizing beams without the disadvantages of the conventional metal latches. The present invention includes an additional retainer clip located at first and second ends of each daughterboard adjacent internal and external stabilizing beams to increase the retention force of the sockets.
The retainer clip of the present invention is configured to be hidden from the user. As discussed above, the retainer clip functions to retain the daughterboard within the socket without any direct displacement by the user during insertion or retraction of the daughterboard.
The retainer clip of the present invention is configured to be loaded into the socket from a bottom surface of the socket. Therefore, the retainer clip is not exposed at the entry location of the daughterboard into the socket. This prevents possible destruction or dislocation of the retainer clip when the daughterboard is inserted into the socket. The retainer clip includes barbs for retaining the retainer clip within the socket. Therefore, the retainer clip is not pushed outwardly from the socket upon insertion of the daughterboard into the socket.
The retainer clip includes a head portion having contoured portion configured to engage a hole or aperture formed in the daughterboard. The shape of the contoured portion of the retainer clip is configured so that top and bottom surfaces of the contoured portion engage an edge of an internal side wall of the daughterboard which defines the aperture in the daughterboard. The bottom surface of the contoured portion has a steep enough angle to provide a positive vertical locking force on the daughterboard while permitting the daughterboard to be removed from the socket when enough force is exerted on the daughterboard. This eliminates the requirement for a user to physically displace or disengage the retainer clip manually. The bottom surface of the contoured portion of the retainer clip is also configured so that the locking angle provided by the retainer clip remains constant regardless how far the contoured portion engages the aperture formed in the daughterboard.
The top surface of the contoured portion provides a lateral force on the daughterboard in a direction normal to the daughterboard and substantially parallel to the motherboard. This lateral force increases the force on a stabilizing beam formed integrally with the socket. Therefore, the retainer clip also increases the frictional retention force of conventional stabilizing beams. The retainer clip secures the daughterboard to the socket to reduce the effects of mechanical shock or vibration on the daughterboard. This increases the reliability of the socket for electrically connecting the daughterboard to the motherboard.
A side surface of the contoured portion of the retainer clip is configured to permit the daughterboard to be removed easily from the socket as the daughterboard is rotated out of the socket. The internal side wall defining the aperture in the daughterboard engages a gently curved ramp surface as the daughterboard is removed. This causes displacement of the retainer clip from the aperture to permit removal of the daughterboard from the socket.
The present invention advantageously increases both the vertical retention force and the horizontal retention force of the daughterboard within the socket. The present invention also permits the daughterboard to be removed from the socket easily without damaging the daughterboard.
According to one aspect of the present invention, a retainer clip is provided for securing a printed circuit board to a socket having an elongated slot for receiving the board therein. The retainer clip includes a retention section for engaging the socket to retain the retainer clip within the socket and a spring section extending upwardly away from the retention section and having an upper distal end. The spring section extends into a plane defined by an edge of the elongated slot. The retainer clip also includes a contoured section formed at the distal end of the spring section. The contoured section is configured to engage an aperture formed in the board to retain the board within the socket.
According to another aspect of the present invention, the contoured section includes a top surface for applying a force against the board in a direction normal to the board and a bottom surface for applying a force against the board in a direction downwardly into said elongated slot. The contoured section further includes a side surface for engaging the board. The side surface provides a ramp for moving the distal end of the spring section relative to the board to disengage the contoured section from the aperture of the board to permit removal of the board from the socket.
A pair of opposing barbs are coupled to the retention section of the retainer clip to secure the retainer clip within the socket. A generally U-shaped base located between the retention section and the spring section. The retainer clip is inserted into the socket from a bottom surface of the socket. The socket is formed to include a generally T-shaped slot for receiving the retention section of the retainer clip therein to secure the retainer clip to the socket. Preferably, the contoured section is formed eccentrically with the distal end of the spring section.
According to yet another aspect of the present invention, a connector is provided for electrically coupling a printed circuit board formed to include an aperture therein to the connector. The connector includes a socket having an elongated slot for receiving the board therein and a plurality of longitudinally spaced electrical contacts configured to be coupled to the board located adjacent the elongated slot. The connector also includes means for stabilizing the board in the socket, and means for retaining the board within the socket. The retaining means including means for engaging the socket to hold the retaining means within the socket and means for engaging the board to increase the retention force on the board within the socket.
The stabilizing means includes an internal stabilizing beam formed on an end for the socket on a first side of the elongated slot and an external stabilizing beam formed on the end of the socket on a second and opposite side of the elongated slot. The internal stabilizing beam includes a contact surface for engaging a first side of the board, and the external stabilizing beam includes a contact surface for engaging a second and opposite side of the board to stabilize the board relative to the socket.
The retaining means increases a frictional force applied by the stabilizing means to the board. In addition, the retaining means applies a downwardly-directed vertical force on the board to secure the board to the socket.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.